There is a common medical requirement for directly introducing drugs into the bloodstream of a patient, or taking blood samples, at an extracorporeal point, e.g., one of the blood conducting tubes between the patient and an artificial kidney. Access to the blood in the tubing is accomplished by inserting a hypodermic needle into the tubing, but insertion of the needle results in problems in resealing the tubing after the needle is withdrawn and in protecting the operator from accidents while inserting the needle.
Morgan U.S. Pat. No. 3,850,202 describes a tubing injection site guard in which an elastomeric tube is placed in the blood line between the ends of two pieces of blood tubing and all three tubes are surrounded by a rigid sleeve having a needle access port. The elastomeric tube is compressed by the sleeve so that the needle hole reseals. This design requires that the blood tubing be cut and adhesively bonded joints formed between the two sections of blood tubing and the sleeve. It would be desirable not to have to cut the blood tubing and not to have to rely on adhesively bonded joints that could fail in use. Also, the compression of the rubber tube cannot be adjusted with use should the built-in compression not provide adequate sealing after a period of time and use.
Morgan U.S. Pat. No. 3,898,988 describes a tubing injection site guard comprising a rigid plastic tube connecting the ends of two pieces of blood tubing; the needle access port is an opening in the wall of the rigid tube which is sealed with a plug of polyurethane or similar material placed under compression by the sides of the opening. This design also requires adhesively bonded joints between the blood tubing and the rigid tube, and does not allow adjustment of the compression on the sealing plug.
Collins U.S. Pat. No. 3,447,570 describes a tubing injection site guard comprising a U-shaped rigid base engaging a latex pad to form a cylindrical space through which the blood tubing passes. While avoiding tubing joints, the latex is not directly compressed against the blood tubing and needle hole, and the compression cannot be adjusted with use should the built-in compression not be sufficient for sealing after a period of use.